Method of making polyolefin bags



Nov. 15, 1966 c. A. copK METHOD OF MAKING POLYOLEFIN BAGS 2 Sheets-Sheet1.

Filed April 19, 1965 CHARLES ACOOK INVENTOR.

Nov. 15, 1966 c, 00K 3,286,005

METHOD OF MAKING POLYOLEFIN BAGS Filed April 19, 1963 2 Sheets-Sheet 2 IPRINTER CHARLES A,COOK

INVENTDR EXTRUDER United States Patent 3,286,005 METHOD OF MAKINGPOLYOLEFIN BAGS Charles A. Cook, Tyler, Tex., assignor to NationalDistillers and Chemical Corporation, New York, N.Y., a corporation ofVirginia Filed Apr. 19, 1963, Ser. No. 274,120 Claims. (Cl. 264-95) Thisinvention relates to a novel method of manufacture of polyolefin typebags and more specifically relates to a method of manufacturing suchbags wherein, after printing on a tube of polyolefin material, the tubeis reinflated and rotated with respect to a pair of subsequentlycollapsing nip rolls. By this method a new crease line is formed along aprinted area of the bag while the original crease line falls along thefront and rear panels of the bag.

Polyolefin bags and the manufacture thereof are well known to the art.Generally, a tube of polyolefin material is drawn from appropriateextrusion die and the tube is thereafter collapsed and the surfaces maybe printed upon. The tube is then transmitted to a bag making machinewhich in essence cuts the tube into a plurality of lengths, one end ofwhich is sealed and the other of which is open, so that individual bagsare formed. In the past such difficulty has been experienced in theopening of the bags and in providing printing for the bags which will beobservable along the edge of the bag when the bag is filled.

In accordance with the invention and after the printing step has beencompleted the tube is reinflated and is caused to be rotated withrespect to a pair of collapsing nip rolls. Thereafter a new crease orbag edge is formed which can lie directly over printing intended to bein the edge of the bag while the original creases fall in the front andrear panels of the bag. Accordingly, when the bag is filled, the sideprinting will be continuous and be easily observable while at the sametime the crease lines in the front and rear panels form lair channelsextending into the bag which permit the easy opening thereof, as isdescribed in the copending application Serial No. 274,119 filed April19, 1963, now US. Pat. No. 3,216,646 titled, Side Printed Easy OpeningPolyolefin Bag.

Accordingly, a primary object of this invention is to provide a novelmethod of manufacture of a polyolefin type bag which can be easilyopened.

A further object of this invention is to provide a novel method ofmanufacture for polyolefin bags which permits the direct printing on thefront or rear panels or both which ultimately becomes the edge of thebag.

These and other objects will become apparent from the followingdescription when taken in connection with the drawings, in which:

FIGURE 1 illustrates a bag printed in accordance with the concepts ofthe present invention.

FIGURE 2 schematically illustrates the unsealed end of the bag of FIGURE1 when the bag is unfilled, to particularly illustrate the formation ofcreases in the front and rear panels of the bag.

FIGURE 3 is a partially diagrammatic and partially perspective view ofthe manner in which the preprinted tube of film is rotated andreinfi-ated and then reclosed prior to the bag forming process.

FIGURE 4 is a side plan view of the twister mechanism of FIGURE 3.

FIGURE 5 is an enlarged detail view which illustrates the manner inwhich the slats of FIGURE 4 may be secured to their side supportmembers.

Referring first to FIGURE 1, there is illustrated therein a novel bagconstruction wherein a bag is comprised of a front panel 10, a rearpanel 11, an edge portion 12, which connects the front and rear panels10 and 11, and sealed ends 13 and 14. The end 13 is a previously sealedend and the bag prior to being filled as shown in FIGURE 2 was open atfront end 14. The front end 14 of the bag is schematically illustratedin FIGURE 2 with the bag collapsed prior to the filling openation. Itwill be noted that the bag of FIGURE 2 has two manufacturers creases 15and 1 6 (crease 16 is seen in FIGURE 1) and additionally has furthercreases 17 and 18 in panels 10 and 11 respectively. The creases 17 and18 provide means for easily opening the bag of FIGURES 1 land 2. That isto say, a typical polyolefin bag of the prior art is difficult to snapopen since the inner surfaces of the front and rear panels tend to sticktogether. In accordance with the invention, however, additional creases17 and 18 run completely along the length of the bag to provide airpassages within the bag [and a thumb hold for ease of opening.

As a further feature of this invention, it can be seen in FIGURE 1 thatprinted information (the label 6N 14 appears directly in the side of thebag and straddles crease line 16. Therefore, when bags of the type ofFIGURE 1 are placed in a large stack, this identifying information isreadily observable as contrasted to prior art type bags which containinformation either on front or rear panels which were hidden from view.

The manner by which the bag of FIGURES 1 and 2 can be manufactured isillustrated in FIGURES 3, 4 and 5. FIGURE 3, is a schematic illustrationof the method of manufacture leading to the printing of an extruded tubewhich ultimately is formed into bags. Thus, in FIGURE 3 there isillustrated an extruder 20 which may be of any desired type well knownto those skilled in the art, which eXtrudes a thin walled tube 21 of anyappropriate polyolefin material.

The tube 21 is grasped at its upper end by appropriate nip roll means 22which is also well known to those skilled in the art, which flattens thetube to an appropriate flat web which is ultimately processed in anydesired manner and then is applied to a printer 23. The printer 23,which may be of any desired type, then pn'nts some repetitive pattern onthe tube moving in the direction of the arrow 24, where the pattern onthe upper side of the web is shown by shading lines while a similarpattern is printed on the rear panel of the web as shown by dottedlines. i

All of the foregoing are steps well known to those skilled in the art,and in the past, the printed web coming down printer 23 is connected toa bag making machine which now cuts the tube into predetermined lengths,one end of which is sealed and the other end of which is open to form abag. web 21 is transmitted to a pair of nip rolls 22 and 23 and througha twisting structure 24 which will be described more fully hereinafter.

Essentially, the purpose of twisting structure 24 is to cause the web 21to rotate. The web 21 emerging from the end of twister 24 is theninflated between the end of twister 24 and a second pair of nip rolls 25and 26 which recolla-pse the lower tube 21a. It is to be specificallynoted, however, that since tube 21a is rotated that when the nip rolls25 and 26 recollapse tube 21a, the original crease line 30 and 31 of web21 will now lie in the front and rear panels 32 and 33 respectively andnew crease lines 34 and 35 are formed for the tube.

In accordance with the invention, however, the

In comparing the flattened tube of FIGURE 3 to the bag of FIGURE 5 is itnow seen that crease line 30 corresponds to crease 17 of FIGURE 2 whilethe other crease line 31 corresponds to crease line 18 of FIGURE 2 toprovide the desired air passages and thumb holds needed for easy openingof the bag. Moreover, it will be seen that the printed pattern, such aspatterns 40 and 41, which were originally on the front and rear panelsof the tube prior to the passage through twister 24, are now directlyover the crease lines 35 and 34 respectively. Therefore, bags formedfrom the flattened tube leaving nip rolls 25 and 26 will, when filledhave the printed material of areas 40 and 41 on the side of the bags. Byway of example, area 41 could be printed with the information 6N-24shown in the edge 12 of FIGURE 1, where this printing is done withconventional printing techniques in the front and rear panels of the bagby the printer 23, although it ultimately appears on the edges of thebag after the twisting operation.

It is to be specifically noted that in a typical manufacturing processit is desirable that the nip rolls 22, 23, 25 and 26 be parallel to oneanother. Therefore, a twisting operation is necessary to rotate tube 21ato the position shown in FIGURE 3. Clearly, however, no twistingoperation is necessary if nip rolls 25 and 26 form some angle to theaxis of nip rolls 22 and 23. That is to say, in accordance with theinvention, it is only necessary that the web be reinflated and thenrecollapsed at a new angle with respect to the axis of the bag.

Where the twisting operation is found desirable, the twister 24 can beprovided as illustrated in FIGURES 3, 4 and 5 by means of a plurality ofspaced slats such as a first group of slats 50 which are supported byend supports 51 and 52 and a second similar group of slats such as slats53 which are supported by end supports 54 and 55. It will be notedparticularly from FIGURE 5 that supports 51 and 55 are parallel to oneanother and are at an angle to the supports 52 and 54. Moreover,supports 52 and 54 are parallel to one another and are spaced from oneanother by end clamps 60 and 61 to maintain a predetermined spacingbetween the faces of slats 50 and 53. In a similar manner, members 51and 55 are held spaced from one another by end clamps 62 and 63 wherebythe other end of slats 59 through 53 are held spaced from one another.

Accordingly, a web twisting area is designed between the opposingsurfaces of slats 50 and 53 to twist the web 21 which rides between thespaced slats in the manner illustrated in FIGURE 3. Slats 50 and 53 aswell as their supports 51 through 55 can be formed of any desirablematerial and can be secured to one another in any desired manner.

By way of example, FIGURE 6 illustrates the manner in which support 52is secured to one end of slat 50, Thus the slat 50 has a countersunkopening 70 therein which receives the head of a bolt 71. Bolt 71 extendsthrough an opening in slat 50 and a cooperating opening in member 52 andis captured on the other side of member 52 by means of an appropriatewasher 72 and nut 73 which is threaded onto the end of bolt 71. Byappropriately loosening these connections it will be clear that thetwisting structure 24 can be rotated to any desired twisting angle withexternal support structure (not shown) thereafter maintaining thestructure in this twisted position with the individual securing meansbetween the supports and the slat being thereafter tightened.

In the foregoing, the invention has been described only in connectionwith the preferred embodiments thereof. Many variations andmodifications of the principles of the invention within the scope of thedescription herein are obvious. Accordingly, it is preferred to be boundnot by the specific disclosure herein, but only by the appending claims.

What is claimed is:

1. The method of manufacturing a polyolefin bag which includes the stepsof drawing a tube of polyolefin material, flattening said tube on afirst and second crease line, reinflating said tube, and reflatteningsaid tube on crease lines removed from said first and second creaselines.

2. The method of manufacturing a polyolefin bag which includes the stepsof drawing a tube of polyolefin material, flattening said tube on afirst and second crease line, reinfiating said tube, and reflatteningsaid tube on two crease lines removed from said first and second creaselines; and thereafter cutting said tube into predetermined lengths toform bags having crease lines in the top and bottom surface thereof topermit ease of opening of said bag.

3. The method of manufacturing a polyolefin bag which includes the stepsof drawing a tube of polyolefin material, flattening said tube on afirst and second crease line, rotating said flattened tube, reinflatingsaid tube, and reflattening said tube on two crease lines removed fromsaid first and second crease lines.

4. The method of manufacturing a polyolefin bag which includes the stepsof drawing and flattening a tube of polyolefin material, passing saidflattened tube through a first nip roll means, rotating said flattenedtube about the axis thereof through an angle less than reinfiating saidtube and thereafter passing said reinflated tube through second nip rollmeans having axes parallel to said first nip roll means to reflattensaid tube.

5. The method of manufacturing a polyolefin bag which includes the stepsof drawing and flattening a tube of polyolefin material on a first andsecond crease line, passing said flattened tube through a first nip rollmeans, rotating said flattened tube about the axis thereof through apredetermined angle, reinflating said tube and thereafter passing saidreinflated tube through second nip roll means having axes parallel tosaid first nip roll means to reflatten said tube on a third and fourthcrease line removed from said first and second crease lines.

6. The method of manufacturing a polyolefin bag which includes the stepsof drawing and flattening a tube of polyolefin material on a first andsecond crease line, passing said flattened tube through a first nip rollmeans, rotating said flattened tube about the axis thereof through apredetermined angle, reinflating said tube and thereafter passing saidreinflated tube through second nip roll means having axes parallel tosaid first nip roll means to reflatten said tube on a third and fourthcrease line removed from said first and second crease line; andthereafter cutting said tube into predetermined lengths to form bagshaving crease lines in the top and bottom surface thereof to permit easeof opening of said bag.

7. The method of manufacturing a polyolefin bag which includes the stepsof drawing a tube of polyolefin material, flattening said tube on afirst and second crease line, printing on at least said top surface ofsaid flattened tube, reinflating said tube, and reflattening said tubeon two crease lines removed from said first and second crease lines.

8. The method of manufacturing a polyolefin bag which includes the stepsof drawing a tube of polyolefin material, flattening said tube on afirst and second crease line, printing on at least said top surface ofsaid flattened tube, reinflating said tube, and reflattening said tubeon two crease lines removed from said first and second crease lines,with at least one of said two crease lines extending through theprinting on said top surface of said flattened tube.

9. The method of manufacturing a polyolefin bag which includes the stepsof drawing a tube of polyolefin material, flattening said tube on afirst and second crease line, printing on at least said top surface ofsaid flattened tube, rotating said flattened tube, reinflating saidtube, and reflattening said tube on two crease lines removed from saidfirst and second crease lines.

10. The method of manufacturing a polyolefin bag which includes thesteps of drawing and flattening a tube of polyolefin material on a firstand second crease line, printing on at least said top surface of saidflattened tube, passing said flattened tube through a first nip rollmeans, rotating said flattened tube about the axis thereof through apredetermined angle, reinfiating said tube and thereafter passing asidreinflated tube through second nip roll means having axes parallel tosaid first nip roll means to reflatten said tube on a third and fourthcrease line removed from said first and second crease lines; at leastone of said first and second crease lines extending through saidprinting on said top surface of said flattened tube.

References Cited by the Examiner UNITED STATES PATENTS 2,838,799 6/1958Meister 26494 2,980,963 4/1961 Makowski 264-132 3,110,554 11/1963 Yazumi264132 3,155,752 11/1964 Reigler 26495 ROBERT F. WHITE, PrimaryExaminer.

ALFRED L. LEAVITT, Examiner.

R. B. MOFFITT, Assistant Examiner.

1. THE METHOD OF MANUFACTURING A POLYOLEFIN BAG WHICH INCLUDES THE STEPSOF DRAWING A TUBE OF POLYOLEFIN MATERIAL, FLATTENING SAID TUBE ON AFIRST AND SECOND CREASE LINE, REINFLATING SAID TUBE, AND REFLATTENINGSAID TUBE ON CREASE LINES REMOVED FROM SAID FIRST AND SECOND CREASELINES.